The present invention relates generally to gas exchange valve assemblies, and more particularly to a gas exchange valve assembly structure for a MonoValve engine.
Gas exchange valves, such as those included in MonoValve hydraulically actuated fuel injectors, are designed to include a relatively large diameter valve portion and a relatively large diameter stem portion positioned on either side of a smaller diameter segment. Because the smaller diameter segment is designed to be positioned in a bore with a diameter smaller than both the valve portion and the stem portion, a gas exchange valve composed of one piece having these characteristics cannot be assembled in a corresponding one piece valve body. Therefore, a gas exchange valve having these characteristics must be augmented to allow for assembly.
The present invention is directed to enabling assembly of valve members that require two large diameter portions to be positioned above and below a relatively small diameter portion in a valve body component.
In one aspect of the present invention, an engine comprises a housing that defines a hollow piston cavity that is separated from a gas passage by a valve seat. The housing further defines a biasing hydraulic cavity and a control hydraulic cavity. A gas valve member is also included in the engine and is movable relative to the valve seat between an open position at which the hollow piston cavity is open to the gas passage and a closed position in which the hollow piston cavity is blocked from the gas passage. The gas valve member includes a ring mounted on a valve piece and a retainer positioned between the ring and the valve piece. A closing hydraulic surface is included on the gas valve member and is exposed to liquid pressure in the biasing hydraulic cavity. Also included on the gas valve member is an opening hydraulic surface which is exposed to liquid pressure in the control hydraulic cavity. The opening hydraulic surface has a larger effective area than the closing hydraulic surface.
In another aspect of the present invention, a gas exchange valve for an engine comprises a hollow valve piece that has a stem portion and a valve portion. The valve portion defines a nozzle outlet and includes an annular valve surface. A ring is mounted around, and in contact with, the stem portion. A retainer is positioned between the stem portion and the ring.
In yet another aspect of the present invention, a monovalve fuel injector comprises an injector body that includes a hollow valve piece which has a stem portion and a valve portion. The valve portion defines a nozzle outlet and includes an annular valve surface. A ring is mounted around, and in contact with, the stem portion. A retainer is positioned between the stem portion and the ring. A pumping element is at least partially positioned inside the hollow valve piece and includes opposing hydraulic surfaces.